Siren for the production of sharp cut tones of short duration



Jan' 1, 1935 B. sET'rEGAs-r 1,985,954

SIREN FOR THE PRODUCTION OF SHARP CUT TONES OF SHORT DURATION ,Filed'NoL6, 1953 Pat-ented Jan. 1, 17935 SIREN FOB. THE

" CUT'TONES PRODUCTION 0F SHARP 0F SHORT DURATION Bernhard Settegast,Kiel, Germany, assig'nor to Echometer Gesellschat t mit beschlilnkterHaftung, l'iiel, Germany, a rm Application November s, '1933, serial No.696,819

Germany November 2, 1932 s claims. (o1. ivi-s) The invention relates toa sound transmitter operated by compressed air which is particularlysuited for the .production of short tones which set in at ful strengthand are 5 and very short duration, as are used in particular for echosounding in air. The characteristic mode of action in this type vofsound transmitter is obtained by the .direct incorporation of'the tonegenerating member with a special comu pressed air container,'whichwithout any intermediate conductor, supplies its content of pressure gasdirectly to the tone generating member. The'control of the inletconstructed as a dili'erential valve through which the compressed airacts on the tonegenerating member, is effected preferablyelectromagnetically, in which case one of the valve plates is designedin the form of a magnet armature.

In the transmitter according to the invention I a siren serves as thetone generating member, in whichthe inset and the end of the tone areparticularly sharp. which much larger amplitudes may be obtained than inother types o! tone generators and which remain absolutely constantduring the tone period.

The construction and mode of action are discussed in the following, withreference to the drawing in which Y l Fig. 1 represents a cross-sectionthrough the tone generating member on the line 2-2 in FiE.2;- e `l'ig. 2represents a longitudinal section through the tone transmitter, and

Fig. 3 represents an enlarged sectional view of the vright-hand upperand lower sectional wall portion of cylinder wall -1 in Fig. 2.

'I'he ca'sing 1 of the tone transmitter is constructed in the form of aclosed hollow cylinder. 'I'hrough the tube connection 2 is effected thesupply lof compressed pressed air from a convenient container. Anelectromagnet 5 is incorporated in the one end of the Ahollow cylinder.Inside the hollow cylinder a double seat valve is arranged axiallydisplaceable on the hollow axle 8. The'valve'plates 3 and 4 areconstructed such that the diameters or surface areas are somewhatdiil'erent from one another. In such an arrangement it is wellknown thatto close the Valve it isonly necessary to overcome the differencebetween' the pressures acting on the diierent valve plates. For thispurpose the one valve plate 3 is lcon tructed as, or combined with, amagnet armann-e. The closing or the valve is etlectedagainst of largeamplitude and above all by the aid of gas, for example, comgized. Ifextremely short signals are to .be given rtransmitter is constructed inthe form of the know sirens. It consists of a bell Shaped rotation body9, the cylindrical rim of `which extends over the lower end, ofthehollow cylinder 1. In this rim are provided a convenient number ofopenings 11 which are disposed opposite to anv with rubber and ail'ord aequal or a smaller number of peripherally spaced rectangular dischargeopenings 10 provided in the periphery of the hollow cylinder 1. 'Iherotation body is carried on a spindle 14 and is driven by an electricmotor 19 over a gearing 18; By means of a special regulator 20 on theelectric motor (not shown in detail), provision is made for maintainingconstant the speed of rotation throughout the duration o1' the signal.

'I'he opening. of the valve orxthe starting o1' the tone is eiiected bythe de-.excitation ofthe electromagnet 5 by opening the switch 12 of acircuit including battery B. 'Ihe double seat valve then moves under thedierential pressure suddenly downwards in the direction ofthe arrow anduncovers the openings 10. The compressed air inside the casing issuddenly released through the openings 10 and ls intermittentlyvdischarged through' openings 11 in therotating body 9, thus producing atone in' well-known manner. The pitch o1' the tone-fis vdetermined bythe number of4 openings and the speed of rotation. In this mannerextremely precise tone impulses of well dened duration and of analmostexplosive character can be emitted.

The return of the double seat valve intoits position of rest'is eiectedunder the iniluence o1' a spring 2 1 and the'attractive .force of theabove mentioned 'electromagnet 5 when ener-- the duration of which-doesnot exceed one hundredth of a second, then it isnecessary to open i theswitch 12 o sists the closing of the valve. For ton oi' short durationit is preferable to for-a very short time. 4In this lcase the remanentmagnetism of magnet 5' as-` make the cross-section o1' the supply tubesmaller than the total l'Ihe form of hollow cylinder area of theopenings inthe siren. the discharge openings 10 in the' and the openings11 in the rotaa given differential pressure 2 tion body has some inuenceon the purity of the tone. For generating a sinusoidal tone, it isnecessary that the periodic pressure fluctuations in the air shouldfollow a sine function. It has been found by calculation that thisrequirement is satisfied if the openings are of rectangular shape.

The transmitter is embraced by a sound funnel 22 which is so disposedon'the hollow body that the sound is radiated in the axial direction.The rim of this sound funnel is provided with a flange which serves forsecuring the sound transmitter in a wall, for example, in the fuselageof an aircraft. 1 This type of transmitter is suited for the generationof Morse signals of a very small duration. The production of the signalsis effected by the aid of the switch '12 which in that case should beconstructed as a Morsel key. On account oi the large consumption of air,however, the crosssection of the supply conduit 2 must be made largerthanin the case where separate tones are emitted at large intervalsoftime.

l. Asound4 trans -itter for producing tones of explosion-like'-precision and intensity by means of a siren, comprising-a pres ire tankfor storing medium actuated by the siren, and having peripherally spacedperforations atits lower end forming the stator of the siren, a rotorand means for continuouslyl operating' it, said rotor surrounding saidstatorand having peripherally spaced perforations disposed to.interstator perforations a differential pressure valve in said containerdisposed to directly control the stator pertorations and tending toexpos directly to the interior oi the pressure tank' under exertedagainst the valve by the operating medium, and controllable means fornormally holding said valve in closing position against said;diiferentialpressure, whereby the tank'can be suddenly dischargedthrough tions when the valve is opened. 2. A sound-transmitter forproducing tones of explosion-like precision and' intensity by` meanstions during the stator perforations of a siren, comprising a pressuretank for storing the pressure medium actuated by the siren, and havingperipherally spaced perforations at its lower end forming the stator ofthe siren, a rotor and means for continuously operating it, said rotorsurrounding said stator and having peripherally spaced perorationsdisposed to intermittently register with saidstaitcr perforatons duringthe continuous operation of the rotor, and a differential pressure valvein said container disposed to directly control the stator perforationsand tending to expose the stator perforations directly to the interiorof the pressure tank under a given differential pressure exerted againstthe valve by the operating medium, and controllable means for normallyholding said valve in closing position against said diierentialpressure, whereby the tank can be suddenly discharged through the sirenperforations when the valve is opened, and a pressure medium supplyconduit connected to said tank and having an area smaller` than the sumof the stator perforation areas.

3. A sound transmitter for producing tones of explosion-like precisionand intensity by means.

of a siren, comprising a pressure tank for storing the pressure mediumactuated by the siren, and having peripherally spaced perforations atits -lower end forming the stator of the `siren, a rotor and means saidrotor surrounding said stator and having peripherally spacedperforations disposed termittently register with said stator perforathecontinuous, operation -of 'the rotor, and a differential pressure'valvein said containerdisposed to directly control the stator perforationsand tending to expose the stator perforations directly to the interiorof the pressure tank under a given Vdifferential pressure exertedagainst the valve by the operatingmedium, and controllableelectromagnetic means for normally holding said valve in closingposition againstsaid differential pressure, whereby the tank can besuddenly discharged through the siren perforations when .the valve isopened.

BERNHARD smfrsoflis'r.

for continuously operating it,

to in-

